In the fictional universe of the Stargate franchise, the people of Earth have encountered numerous extraterrestrial races on their travels through the Stargate. In addition to a diversity of alien life, there is also an abundance of other humans, scattered across the cosmos by advanced aliens in the distant past. Some of the most significant species in Stargate SG-1 are the Goa'uld, the Asgard, and the Replicators. Stargate Atlantis, set in the Pegasus galaxy, introduced the Wraith and the Asurans. One of the most influential species in Stargate, the Ancients, have moved on to a higher plane of existence. For practical reasons of television productions, almost all of the alien and human cultures in the Stargate's fictional universe speak native English. Because of the time constraints of an hour-long episode, it would become a major hindrance to the story each week if the team had to spend a sizeable part of each episode learning to communicate with a new species.[1]

Stargate SG-1 explains the human population in the Milky Way galaxy by revealing that the alien Goa'uld transplanted humans from Earth to other planets for slave labor. Many of these populations were subsequently abandoned, often when deposits of the precious fictional mineral naqahdah were exhausted, and developed into their own unique societies.[2] Some of these extraterrestrial human civilizations have become much more technologically advanced than Earth, the in-show rationale being that they never suffered the setback of the Dark Ages. The most advanced of these humans were the Tollan, although they were destroyed by the Goa'uld in Season 5's Between Two Fires.[3] The human populations of the Pegasus galaxy are the product of Ancient seeding.[4] few human races in Pegasus are technologically advanced, as the Wraith destroy any civilization that could potentially pose a threat.[5] There are also large numbers of humans in the Ori galaxy, where they empower the Ori through worship.[6]

Stargate SG-1 takes place mostly in the Milky Way galaxy. Brad Wright and Jonathan Glassner tried to stay true to the feature film, but also wanted Stargate SG-1 to be unique in its own way.[7]Stargate SG-1 gradually evolved away from the basic premise of the film and developed its own unique mythological superstructure.[8]Stargate SG-1 elaborated on the film's Egyptian hybrid mythology and mixed in other historical mythologies, coming up with a mythological superstructure that explains the existence of all of the other mythologies in the overarching Stargate narrative.[9] The series expands upon Egyptian mythology (notably the Egyptian gods Apep/Apophis, and Anubis as Goa'uld villains), Norse mythology (notably the god Thor as an Asgard ally), Arthurian legend (notably Merlin as an Ancient ally), and many other mythologies like Greek and Roman mythology. SG-1 does not introduce new alien races as often as some other science fiction television series.[10] Most civilizations that the Goa'uld had transplanted maintain much of their original Earth culture, and Stargate SG-1 does not equate civilization with technology like many other sci-fi shows do.[11] Newly encountered races or visited planets are integrated into the mythology, although plotlines of individual episodes are often new, self-standing and accessible for new audiences, giving a compelling internal coherence.[12]

Stargate Atlantis is set in the Pegasus Galaxy and explores the adventures of an "elite expedition" from Earth. The gate address to the legendary city Atlantis is discovered on Earth by Daniel Jackson at the end of 7th season start of the 8th season of Stargate SG-1. The Earth expedition has a multi-nation civilian leadership and a predominantly United States military faction providing security. The intent of establishing a diplomatic mission with inhabitants of the galaxy and a permanent human base in the city of Atlantis for scientific and military research and exploration are driving goals for the humans.[13]

Stargate Universe was conceived as "a completely separate, third entity" in the live-action Stargate franchise.[14] Although it is firmly entrenched in pre-established Stargate mythology, Stargate Universe has diverged in a new direction.[15] Like the first two series in the franchise, Stargate Universe takes place during the present time, not in the distant future.[14]

The show is set on the Ancient ship Destiny. Destiny was part of an Ancient experiment to seed the universe with Stargates millions of years ago but which was lost because of the Ancients' ascension. Ships were sent ahead of the Destiny to seed the universe with Stargates. The Destiny itself was intended to follow a pre-programmed course to explore these galaxies; the Destiny was left unmanned at the time of the Ancients' ascension. To reach this ship, an address would have to be dialled consisting of nine chevrons. The destination of this ninth chevron was previously unknown.[16] The series starts when a team of soldiers and scientists from Earth step through the Stargate to find the Destiny[17] after their base is attacked; unable to return to Earth, they must fend for themselves aboard the ship as it takes them to the far reaches of the universe.[18][19][20] The show was more serialized than its predecessors.[21]

The show is more relationship-based and more arc-driven[22] and will involve more space-based action than SG-1 or Atlantis.[18] "Survival and sacrifice" were the two main themes that were discussed at the preliminary script stages of the show,[23] and the first episode deals with a failing life support system.[24]Stargate Universe will be "a lot darker" than the previous Stargate series,[25] although humor will remain part of the franchise.[26] The show focuses mostly on the people aboard the ship instead of planet-based exploration,[22] and in Brad Wright's words will be "hopefully exploring the truly alien, and avoiding the rubber faced English-speaking one".[26] Despite the focus on survival, the show "will also focus on exploration and adventure – and, by extension, the occasional alien encounter as well".[27] A single dominant villain race like on SG-1 and Atlantis are not featured.[26]

A Stargate is a fictional device that allows practical, rapid travel between two distant locations. The first Stargate appears in the 1994 film Stargate, and subsequently carries over to Stargate SG-1 and its spin-offs. In these productions the Stargate functions as a plot generator, allowing the main characters to visit alien planets without the need for spaceships or any other fictional technology.

Within the Stargate fictional universe, Stargates are large metal rings with nine "chevrons" spaced equally around their circumference. Pairs of Stargates function by generating an artificial stable wormhole between them, allowing one-way travel through. The symbols on the inner ring of the Stargate correspond to constellations and serve to map out coordinates for various destination planets.[2][28] A typical Stargate measures 6.7 m (22 ft) in diameter, weighs 29,000 kg (64,000 lb),[29] and is made of the fictional heavy mineral "naqahdah".[2] The Stargates were created millions of years ago by an alien race known as the Ancients;[30] their modern history begins when EgyptologistDaniel Jackson deciphers their workings in the Stargate film.[28]

The Stargate device sets apart SG-1 from other science fiction shows by allowing modern-day people to travel to other planets in an instant,[31] although scholar Dave Hipple argued that SG-1 "also deploys [science fiction] stereotypes both to acknowledge forebears and to position itself as a deserving heir".[32] With the help of the central Stargate device, the premise of Stargate SG-1 combines ancient cultures, present-day political and social concerns, aliens and advanced technologies.[8] Near-instantaneous interplanetary travel allows a fundamental difference in plot structure and set design from other series. There is a disjunction between politics on Earth and the realities of fighting an interstellar war.[33] The Stargate also helps to speed up the exposition of the setting.[12]

The Ancients are the original builders of the Stargate network. At the time of their introduction in SG-1 '​s "Maternal Instinct" (season 3), they have long Ascended beyond corporeal form into a higher plane of existence. The humans of Earth are the "second evolution" of the Ancients. The Ancients (originally known as the Alterans) colonized the Milky Way galaxy millions of years ago and built a great empire. They also colonized the Pegasus galaxy and seeded human life there, before being driven out by the Wraith. The civilization of the Ancients in the Milky Way was decimated thousands of years ago by a plague, and those who did not learn to ascend died out. With few exceptions, the ascended Ancients respect free will and refuse to interfere in the affairs of the material galaxy. However, their legacy is felt profoundly throughout the Stargate universe, from their technologies (such as Stargates and Atlantis, to the Ancient Technology Activation gene, that they introduced into the human genome through interbreeding) as well as many of the antagonists in the series, having resulted from failures or negligence on the part of the Ancients.

The Ancients were a small percentage of the Alteran Population, the remainder focused more on religious pursuits than scientific ones. Upon ascending to their higher plane of existence, they discovered ways of gaining strength by convincing material humans to abandon their wills to the ascendants' desires. The Ori created the religion of Origin to gain power from the humans who practiced their religion. Priors, missionaries of the Origin religion, attempted to forcefully introduce their belief system to the Milky Way Galaxy. Their ways of conversion brought forth indiscriminate intimidation, terror and consequences. The people of Earth fought vehemently against this oppressive force and encouraged the people of the Milky Way Galaxy to defend their cultures and beliefs. The ascended Ancients did not become involved in the struggle and thereby allow the humans from Earth to maintain their role as heroic defenders.[10]

Aschen[34] are a bland and humorless advanced people from a world designated P4C-970. They have the ability to manufacture biological weapons to specifically target a certain species in certain ways (e.g. sterilization). In the Episode 2001[35] it is mentioned that they have arrived to the Volian's planet (P3A-194) with spaceships. So although they are not a pioneer type the can do interstellar traveling. Further they have the ability to turn a Jovian type planet into a second sun to increase crop yields and also possess a form of teleportation.

A benevolent race that, according to the mythology of Stargate, gave rise to Norse mythology on Earth and inspired accounts of the RoswellGreys. The Asgard can no longer reproduce and therefore perpetuate themselves by transferring their minds into new clone bodies as necessary. Extremely advanced technologically, the threat of their intervention shields many planets in the Milky Way from Goa'uld attack, including Earth.[36] They also provide much assistance to Earth in the way of technology, equipment, and expertise. Their main adversary in Stargate SG-1 are the mechanical Replicators, against which they enlist the aid of SG-1 on several occasions. The entire Asgard civilization chooses to self-destruct in "Unending", due to the degenerative effects of repeated cloning. A small rogue colony of Asgard, known as the Vanir, still exist in the Pegasus galaxy. They were able to slow cloning's diminishing returns by experimenting on humans.

Artificial life-forms composed of nanites, introduced in season 3 of Stargate Atlantis. They are similar to the human-form Replicators of Stargate SG-1 and so are called that in the show. The Asurans were created by the Ancients to combat the Wraith but were ultimately abandoned for being too dangerous. Extremely aggressive, the nanites thrived and built an advanced civilization. In season 4, Rodney McKay activates the Asurans' attack code, causing them to attack the Wraith, but this eventually comes to threaten all the inhabitants of Pegasus as the Asurans decide the best strategy is to starve the Wraith by eliminating all human life in the galaxy.

The Berzerker drones are a robotic war system with attack drones and motherships to control them. They appear to attack and destroy all not-self spacecraft. The Destiny crew speculate that their parent civilization is long dead, and that they just carry out their mission to destroy all non-native technology, destroying other races along the way.[37]

These bugs give the illusion of sand floating around. They can consume large volumes of water at a rapid rate considering they are such small entities. They seem to be intelligent creatures and are passive and helpful unless provoked, in which case they can be extremely lethal. They fly around in "swarms" and will attack together. They were the first species to be encountered in the Destiny expedition, though they were initially dismissed as a hallucination suffered by Matthew Scott. The creatures appeared to develop a rapport with Scott and aided him in his quest for Lime after he offered them water as a test of their sentience. The creatures also revived him on their home world when he collapsed due to the heat, through burrowing into the ground to release some water to wake him.

The Furlings are revealed as one of the alliance of four great races in "The Fifth Race", but virtually nothing else has been revealed about them in the series. In "Paradise Lost", Harry Maybourne leads SG-1 to a Furling teleportation arch that leads to an intended Utopian colony. Furling skeletons were originally planned to be featured in the episode, but the production of such proved to be too expensive.[38]Jack O'Neill concludes that the Furlings must be cute and cuddly creatures, based solely on their name. In "Citizen Joe", another character equates the Furlings to Ewoks based on their name.

The length of time that the Furling nature has remained a mystery in the series has given the producers the opportunity to tease fans with a running gag. When Executive Producer Robert C. Cooper was asked "Will we ever meet the Furlings?", his answer was "Who says we haven't?".[39] The writers later went on to state that although we have seen Furling technology and the Furling legacy, no actual Furling has ever appeared on the show. Joseph Mallozzi claimed that more about the Furlings would finally be revealed in Stargate SG-1's tenth season.[40] In a Sci Fi Channel advertisement for the 200th episode, Cooper stated that "We're finally going to get to see the Furlings." What was actually shown was an imagined scene from a script for a movie based on the fictional television series "Wormhole X-Treme!", a parody of Stargate SG-1 set in the Stargate SG-1 universe. The Furlings were depicted as Ewok-like, or Koala-like creatures that are destroyed by the Goa'uld soon after making contact with SG-1.

Gadmeer The society of the Gadmeer was a peaceful and technologically advanced one that lasted for over 10,000 years. Over a thousand years ago they were defeated by a superior power due to a lack of military technology and tactics, and thus their race apparently died out. To prevent their culture from vanishing they built a giant vessel which stored all their knowledge, including arts, mathematics and even the DNA samples of thousands of the plants and animals of their homeworld. [41]

The Goa'uld are the dominant race in the Milky Way and the primary adversaries from seasons 1 to 8 of Stargate SG-1. They are a parasitic species that resemble finned snakes, which can burrow themselves into a humanoid's neck and wrap around the spinal column. The Goa'uld symbiote then takes control of its host's body and mind, while providing longevity and perfect health. Thousands of years ago, the Goa'uld ruled over Earth, masquerading as gods from ancient mythologies. They transplanted humans throughout the galaxy to serve as slaves and hosts, and they created the Jaffa to serve as incubators for their larvae. The most powerful Goa'uld in the galaxy are collectively known as the System Lords.

The Goa'uld are the first and most prominent alien race encountered by the SGC, and also one of the few nonhumanoid species to appear in the early seasons of the series. The Goa'uld are branded as evil by their pretending to be gods and forcing people to submit to their quasireligious pronouncements.[10]

The humans of Earth play a central role in the story and mythology of the Stargate fictional universe. According to the Stargate film and Stargate SG-1, the parasitic Goa'uld ruled Earth thousands of years ago, posing as gods of ancient Earth mythologies, and transplanted Earth humans throughout the galaxy via the Stargate. Thus, the Goa'uld and their Jaffa servants know the humans of Earth as the "Tau'ri" (/ˈtɔri/ or /ˈtaʊəri/), which means "the first ones" or "those of the first world" in their fictional language.[2] Earth is also known as "Midgard" by offworld humans protected by the Asgard, who masquerade as Norse gods.[42][43]Stargate SG-1 further extended the backstory of Earth humans by introducing the Ancients, an advanced race of humans from another galaxy. The Ancients regard the humans of Earth as their "second evolution",[44] and some of their number merged with primitive human populations 10,000 years ago after they returned to Earth from Atlantis.[4]

Five thousand years ago, the people of Earth rose up against their Goa'uld oppressors, and buried their Stargate.[28] The modern history of Earth and the Stargate begins when it is unearthed in Egypt in 1928. The device is brought to the United States in 1939 to keep it out of Nazi hands and eventually installed in a facility in Creek Mountain, Colorado (Cheyenne Mountain in Stargate SG-1).[28] In the events of the Stargate film, Dr. Daniel Jackson deciphers the workings of the Stargate and a team is sent through to the planet on the other side. In "Children of the Gods", taking place a year after the film, Stargate Command is established in response to an attack by the Goa'uld Apophis, and given the mandate to explore other worlds and obtain technologies that can be used to defend Earth. In the Stargate SG-1 spin-off Stargate Atlantis, the people of Earth establish a presence in the Pegasus galaxy. The ancients who occupied Atlantis in the Pegasus galaxy are often referred to as the "Atlanteans" (or simply "Lanteans"), after their occupation of Atlantis.

The writers had to strike a balance in the interaction between the explorers from Earth and advanced races (of which there were only few in the story) so that alliances could be developed where the advanced races do not give Earth all their technology and knowledge.[45]Stargate SG-1 emphasized its present-day-Earth story frame by frequently referencing popular culture, like The X-Files and Buffy the Vampire Slayer had done before.[32] According to one critic in 1997, Stargate SG-1 was designed to have no nationality, which might appeal to viewers all over the world.[46] The final episodes of season 7 (2004) brought a more global approach to the scenario when the Stargate Program was revealed to over a dozen nations, which further helped the international appeal of Stargate SG-1.[47]

A new race created by the Wraith Michael, first seen in "Vengeance". After being outcast by his own kind, Michael sought to combine iratus bug and human DNA to create new followers with the strengths of the Wraith but not their weaknesses. He destroys the Taranians, amongst others, as test subjects for his experiments. The first Hybrids are bestial in appearance, with carapaces and claws. The two-part episode "The Kindred" reveals that Michael has created more "refined" Hybrids using the abducted Athosian population. These Hybrids resemble the Wraith, but do not need to feed on humans. In "Search and Rescue", many of the Hybrids are killed by the destruction of Michael's cruiser, and the rest are captured by the Atlantis Expedition. They are transformed back into their original selves using Beckett's retrovirus. They are interred in a camp on the mainland by the IOA,[48] before being allowed to return to their people.[49] In the episode "Whispers", an Atlantis team discovers one of Michael's labs, containing earlier versions of his Hybrids that incorporate DNA from several other organisms in addition to the iratus bug. These vicious creatures are blind and hunt by sound, and can extrude a fog from gill slits on their necks that interferes with electronics.

The Jaffa (usually pronounced jah'FAH) are modified humans genetically engineered by the Goa'uld in antiquity to serve as soldiers and as incubators for their young. Their story is primarily told through Teal'c. The main difference between a Jaffa and a normal human is an abdominal pouch accessible from the outside by a X-shaped slit.[2] The pouch serves as an incubator for a larval Goa'uld. Implanted during a "coming of age" rite known as a prim'tah, the pouch improves the Goa'uld's ability to successfully take a host upon maturation from 50% to nearly 100%. The Goa'uld have a device capable of quickly transforming humans into Jaffa.[50] The larval symbiote grants the Jaffa enhanced strength, health, healing, and longevity (more than 150 years). However, the presence of the symbiote also replaces the Jaffa's immune system, and if removed the Jaffa will die a slow and painful death that can only be avoided by either acquiring a new symbiote or by lifelong regular injections of the drug tretonin which replaces the Goa'uld functions in the Jaffa body.[51] The Jaffa equivalent of puberty is the Age of Prata, at which time a prim'tah must be performed.[52] Jaffa do not require sleep, but must engage in a form of meditation called kel'no'reem to synchronize with their symbiote.[53] It is possible for a Jaffa to communicate with his/her symbiote through a dangerously deep state of kel'no'reem.[54]

Jaffa who are in service of a Goa'uld bear a black tattoo of their master's insignia on their foreheads. The highest-ranking Jaffa in the service of a Goa'uld is known as the First Prime and bears a raised gold insignia, made by baring the bone with a special knife and filling the wound with molten gold; Teal'c describes it as a painful process. Other high-ranking Jaffa may bear similar silver marks. The elite guard of powerful Goa'uld sometimes wear helmets shaped like that Goa'uld's symbolic animal; the helmets are made from articulated metal plates that can fold to reveal the face, and are intended to intimidate the Goa'uld's enslaved human populations. Helmeted Jaffa seen or mentioned in the series include the Horus Guards (falcon-headed, serving Ra and Heru-ur),[28][55] Serpent Guards (cobra-headed, serving Apophis),[2] and the Setesh Guards (Set animal-headed, serving Seth).[56] A jackal-headed (Anubis) guard also appears in service of Ra in the Stargate movie.

SG-1 encounters three notable Jaffa factions. The Hak'tyl ("liberation"), introduced in "Birthright", are a group of female Jaffa warriors founded by Ishta, High Priestess of the Goa'uld Moloc. When Moloc ordered that all female children born to his Jaffa be sacrificed, Ishta began secretly saving them on the planet Hak'tyl. The SGC assassinates Moloc in "Sacrifices". The Hak'tyl are a significant power in the Free Jaffa Nation, and are represented by Ka'lel on the High Council.[57] The Sodan are introduced in "Babylon" as a legendary group of Jaffa who, over 5,000 years ago, realized that the Goa'uld were not gods and rebelled against their Goa'uld master Ishkur. The Sodan worship the Ancients and seek Ascension as their ultimate goal. They do not have tattoos on their foreheads specifying allegiance to any System Lord. They are massacred by one of their own who had been infected by a Prior in "Arthur's Mantle". The third Jaffa faction are the Illac Renin ("Kingdom of the Path"), who follow Origin in the belief that the Ori will Ascend them upon death. Their leader, Arkad, is killed by Teal'c in "Talion".

Also called Anubis drones or Supersoldiers, the Kull Warriors are creatures created by the Goa'uldAnubis as a personal army to replace his Jaffa as foot soldiers. They consist of a genetically engineered humanoid form given life using Ancient healing technology, and implanted with a mentally "blank" Goa'uld symbiote to make it subservient. This results in a creature that is utterly obedient to its master.[58] A Kull Warrior possesses much greater strength and stamina than a human and are relentless and single-mindedly focused on their goal; they will ignore any enemies that stay out of their way.[58] The Kull Warrior is bonded to armour that is impervious to almost all firearms, energy weapons, and explosives. Stargate Command and the Tok'ra eventually find a way to counteract the Kull Warriors' life-sustaining energy.

One of the alliance of four great races, the Nox are a fairy-like people encountered by SG-1 on P3X-774 in "The Nox". They want nothing to do with humanity, viewing them as "young" and having "much to learn". The Nox can live to be hundreds of years old and have a great desire for wisdom and understanding. They are extreme pacifists and never employ violence for any reason, even to defend themselves. As they have the ability to render themselves and other objects invisible and intangible, as well as the ability to resurrect the dead, they never need to fight. They also have the ability to activate a Stargate wormhole without the use of a DHD. Although they outwardly seem to be primitive forest-dwellers, they possess advanced technology beyond that of the Goa'uld, including a floating city.[59] The Nox also appear in "Enigma" and "Pretense".

Not much is known of this species, but they seem to be a highly advanced race who are eager to obtain Destiny's secrets. They have attacked Destiny with the intention of boarding it on numerous occasions. They kidnapped Rush and Chloe in an attempt to gain key knowledge of destiny. During their captivity a locator beacon was implanted in Rush's body which enabled the aliens to track Destiny.

A major threat in the cosmos, the Ori are Ascended beings who use their advanced knowledge of the universe to force lesser beings to worship them. In essence, they used to be Ancients, however they split into separate groups due to different views of life. The Ori are religious while the Ancients prefer science. The Ori sway lesser-developed planets into worshiping them by promising Ascension through an invented and empty religion called "Origin". This religion states that they created humanity and as such are to be worshiped by their creations. It also promises its followers that, on death, they will Ascend. However, Origin was designed to channel energy from the human worshipers to the Ori. As such, the Ori never help anyone else Ascend because then they would have to share the power that they sap from their worshipers. Their ultimate goal is to completely destroy the Ascended Ancients, who they know as "the Others". All of their efforts, including their technology, are for the purpose of garnering worshipers.

As Ascended beings, the Ori do not interfere directly in the mortal plane. They use instead humans called Priors, which they artificially evolve so that they are one step from Ascension, giving the Priors godlike powers. Because the Ori have worshipers across the entire home galaxy of the Ancients, and use their knowledge to spread, they are nearly unstoppable. For example: Ori warships, built using conventional means while operated through the supernatural abilities of the Priors, are generally considered to be the most powerful vessels in the Stargate universe.

The Ori might be regarded as a shadow form of the Goa'uld, with the significant difference that the Ori promise transcension to their followers but never provide it.[10] The moral balance between the Ancients and the Ori clearly echoes that of the Goa'uld and the Tok'ra.

Reol The Reol are a race of humanoid aliens, supposedly from the Milky Way. They are a peaceful race who were almost wiped out by the Goa'uld. They were forced to abandon their home world because of the Goa'uld. Reol have a unique natural defense; one of their bodily secretions is used to create false memories and illusions when it comes into contact with a living creature. Their appearance are tall, lanky bipedal creatures with thick strands of hair and dark black eyes. Their heads appear almost skeletal in shape. The Reol have also decided not to embrace technology to the extent that no other species have. [41]

A potent mechanical lifeform using a kiron-based technology composed of building blocks using nanotechnology. They strive to increase their numbers and spread across the universe by assimilating advanced technologies. They are hostile to all other lifeforms in the universe, but are opposed primarily by the Asgard. In the episode "Unnatural Selection", the Replicators had developed human-form Replicators, based on the technology they extracted from their Android creator, that appear just like humans and are able to change their form. Standard Replicators are resistant to energy weapons, and can only be destroyed by projectile weapons. Human-form Replicators, on the other hand, are resistant to projectile weapons as well due to the change in their nature from large blocks to smaller units the size of organic cells (cell blocks).

In the episode "New Order (Part 2)", an Ancient weapon called the Replicator Disruptor was developed by Jack O'Neill while he still had the knowledge of the Ancients in his mind. It works by blocking the cohesion between the blocks that make up the Replicators. The Replicators in the Milky Way galaxy were wiped out by the Dakara Superweapon in the two-part episode "Reckoning" at the climax of Season 8. It has been indicated that the Asgard used the same technology to defeat the Replicators in their own home galaxy as well.

Re'tu: Invisible non-humanoid aliens. A small terrorist like group of these beings wage war on the Goa'uld by eliminating humans as their potential hosts. They operate in 5-man suicide units, which are capable of setting off an explosion equivalent to a small tactical nuke.

Sakari: An ancient silicon-based lifeform, which uses severe hallucinations into manipulating others. The Sekkari are an extinct civilization that distributed devices across the Pegasus galaxy. These "seed carriers" contained the means to begin their evolution again on other worlds, as well as a repository of knowledge to tell the Sekkari descendants everything that once was. They are also the only known silicon-based lifeform in both the Pegasus and the Milky Way galaxy.[41]

The Unas (meaning "First Ones") are the original hosts used by the Goa'uld on their homeworld of P3X-888, first seen in "Thor's Hammer". A race of large and primitive humanoids, the Unas possess great physical strength and have been exploited for physical labor by both Goa'uld and humans.[60][61] Their strength is enhanced even further when they are taken as Goa'uld hosts, and the symbiote is additionally able to heal even grievous injuries.[42][62]

The Unas are a tribal society living in close-knit communities with defined territories. Each tribe is led by a dominant alpha male leader.[61][63] They have limited stone age-level technology, but are more culturally sophisticated than is apparent at first glance and have established codes of behavior and honor. One of the most valuable possessions of an Unas is a necklace made of bone, which prevents Goa'uld symbiotes from burrowing into their necks.[63] The Unas speak their own language that varies between planets but is close enough to be mutually intelligible.[61] Only Goa'uld-possessed Unas have been shown to speak any language other than their own.[42] In "The First Ones", Daniel Jackson is able to decipher the Unas language and befriend a young Unas named Chaka.

In "Beast of Burden", it is shown that a race of humans from another unnamed world use Unas as slaves. A group of slavers from this planet learn the location of the Unas home world, and launched an expedition to capture more Unas. On this expedition, Chaka was captured. SG-1 subsequently followed them to rescue Chaka, and although they were successful, Chaka chose to remain on the planet to lead a rebellion to free his people.

The Ursini[64] first appear in "Awakening". They are small bipedal aliens, but are agile. Their skin is a greenish grey color. They were in pods when Destiny docked with the Seed Ship. These pods were subsequently found aboard a heavily damaged ship floating in space. The pods were uninhabited this time. When Telford was stranded on the Seed Ship with them, they used the pods to transfer their knowledge to him (by the use of a neural interface), and together they repaired the Seed Ship. Eventually coming to Destiny's rescue when it was being attacked by the same Drone Ships that destroyed the Ursini's ships.[65] It is learned that the seedship Ursini are the last of their race, as no communication with any other Ursini can be established. The Ursini die with the seedship on an attack run on the second Drone Command Ship.[37]

A vampire-like telepathic race who feed on the "life-force" of humans. While intelligent humanoids, they are genetically close to insects. They evolved in the Pegasus galaxy after a human population seeded by the Ancients was fed upon by an insect called the irratus bug, which has the ability to draw upon a human's life to heal itself. As they fed, the bugs incorporated human DNA into themselves, giving rise to the Wraith.[66] The Wraith too feed on humans, treating them akin to livestock and regarding the act of feeding as nothing more than natural predation.[4] Their existence is restricted to waking en masse every few centuries to replenish their health by galaxy-wide abductions of humans called "cullings." A small selection of Wraith were tasked with remaining active during this time to maintain watch on the galaxy to prevent human reprisals.[4]

The main antagonists in Stargate Atlantis, the Wraith, are the dominant species in the Pegasus Galaxy. They are biologically immortal hive-based humanoids who feed on the "life-force" of humans, causing them to "lose years" in a way similar to aging. The Wraith drove the Ancients out of Pegasus 10,000 years ago; they now maintain the human worlds of the Pegasus Galaxy as sources of food. The arrival of the Atlantis Expedition in the Pegasus Galaxy leads to the Wraith waking prematurely from their hibernation; the human population of the Pegasus Galaxy is not enough to sustain all of the waking Wraith. To sate their hunger, the Wraith try to get to Earth whose population is much bigger than that of the whole Pegasus Galaxy. This can only be achieved either through the Stargate or by getting more advanced Hyper drive technology, both of which are present in Atlantis. After the expedition tricked them into thinking the city was destroyed, the Wraith began a brutal civil war.

One Wraith, whom Sheppard named Todd, was particularly cooperative after he was rescued from the Genii by him; Todd subsequently aides the expedition's efforts for mutual gain.

Although most known habitable planets in the Stargate universe are populated by humans, there was once an Alliance of four great races. A strategic alliance of the four advanced species was built over many millennia since before the rise of the Goa'uld. In "The Torment of Tantalus", SG-1 discovers a meeting place for the alliance on the planet Heliopolis. There they find a chamber showing the written languages of the four races, as well as a hologram of a common language based on graphical representations of the 146 known (to them) chemical elements. In the season 2 episode "The Fifth Race", Jack O'Neill learns from the Asgard that the alliance consisted of the Ancients, the Asgard, the Furlings, and the Nox. The Asgard also say that humanity has taken the first steps towards becoming "the Fifth Race". In the Stargate SG-1 finale "Unending", Thor declares the Tau'ri are the Fifth Race.

The Tok'ra (literally "against Ra", the Supreme System Lord) are a faction of Goa'uld symbiotes who are opposed to the Goa'uld culturally and militarily. Spawned by the queen Egeria, they live in true symbiosis with their hosts, both beings sharing the body equally and benefiting from each other. Although they have few members, the Tok'ra have fought the Goa'uld for thousands of years, favoring covert tactics and balancing the various System Lords against one another. Since season 2 of Stargate SG-1, the Tok'ra have become valuable allies of Earth.

The Athosians are a group of hunters, farmers, and traders from the planet Athos. First introduced in "Rising", they are the first humans encountered by the Atlantis Expedition in the Pegasus galaxy. The Athosians were once technologically advanced, but reverted to a pre-industrial state to avoid the Wraith. Following their contact with the Expedition, the Athosians move to Lantea and their leader, Teyla Emmagan, joins Major Sheppard's team. In "The Gift", it is revealed that some Athosians possess Wraith DNA, resulting from an old Wraith experiment to make humans more "palatable". This allows these individuals to sense the presence of Wraith, to tap into their telepathic communications, and to control Wraith technology. In the third season episode "The Return", the Athosians are asked to leave Lantea by a group of surviving Ancients reclaiming Atlantis from Earth. The Athosian population is subsequently found to have disappeared from New Athos in "Missing". The search for the missing Athosians and their fate at the hands of the rogue Wraith Michael contributes to a major plot arc near the end of the fourth season.

The Genii appear to be simple farmers, but are in fact a military society with technology comparable to 1940s Earth. First appearing in "Underground", the Genii were once a formidable human confederation until the Wraith vanquished the Ancients 10,000 years ago, and the subsequent victory forced them into hiding in subterranean bunkers during cullings. They have since built their entire civilization underground, and devoted their existence to developing technology such as fission bombs to destroy the Wraith. Their collective desire for revenge has made them paranoid and hostile towards others and they pursue their aims regardless of the cost to anyone else. They become enemies of the Atlantis Expedition in the first season when they attempted to seize an SG team's puddle jumper and weapons, and once try to invade Atlantis,[67][68] though after a coup d'etat in the second season they have been more favorable towards cooperation with the city.[69]

The Satedans are the people of Ronon Dex, who joins the Atlantis Expedition in the season 2 episode "Runner". In that episode, it is revealed that the Satedans were a civilization comparable in technology to Earth in the mid-20th century, but met the fate of all advanced civilizations in Pegasus when their homeworld Sateda (P3R-534) was devastated seven years ago by the Wraith. In "Trinity", Ronon discovers that some 300 Satedans survived the attack in shelters west of the capital and later moved onto other planets like Ballkan and Manaria. In "Reunion", Ronon encounters more Satedans, his former military comrades, who have been converted into Wraith worshipers.

The Travelers are humans who live on a fleet of ships to avoid the Wraith, introduced in "Travelers". Although not as technologically advanced as the Ancients, the Travelers possess hyperdrives and advanced weapons. Due to their population outgrowing their available space, the Travelers had been forced to abandon some of their people on planets. Their discovery of an Aurora-class battleship promised to solve this problem, but without the ATA gene they were unable to operate it. They kidnap John Sheppard and extort him to create an interface for them. Though uncooperative at first on account of his abduction, Sheppard and the Traveler leader Larrin eventually came to an understanding after a mutual experience with the Wraith. In "Be All My Sins Remember'd", the Travelers become concerned by the Asuran Replicator threat after one of their trading partners is wiped out. Several of their ships, including their Ancient battleship, join the Atlanteans and the Wraith in battling the Replicators over their homeworld. According to producers Joseph Mallozzi and Paul Mullie, the Travelers were created as a "wild card" like the Genii, but with advanced technology that would make them a "challenge" for the Atlantis team. Their lifestyle was devised as a way around the established fact that the Wraith wipe out any civilizations that approach them in technological advancement.[70]

Dakara is the planet where the Ancients first landed in the Milky Way Galaxy after fleeing the Alteran Galaxy. It is here where they later built a powerful device, capable of destroying existing life or creating it where there was none before, long before the galaxy was colonized by the Goa'uld or the humans.[71] Long after the Ancients disappeared, the Goa'uld System Lords eventually took possession of the planet, unknowing of its history. The place eventually became a holy ground for their Jaffa servant race since they held legends which described Dakara as the planet where their enslavement began. At the Temple of Dakara, Jaffa were given their strength and longevity through the first implantation of symbiotes. The temple is therefore the ultimate holy ground of the Goa'uld, who kept the Jaffa loyal by propagating lies that they were gods. The idea of stepping into Dakara was unthinkable to the free Jaffa.[72]

After the Replicators start to invade the galaxy in season 8, killing Goa'uld and taking over their fleets, Bra'tac and Teal'c decide this to be the best time to take over Dakara. Dakara easily falls to the rebellion, and the capture of the planet proves to the majority of Jaffa still in servitude that the Goa'uld were not in fact gods. This leads to a general revolt by the Jaffa against their masters. Also, the final battle with the Replicators occurs here which results in their destruction by the Dakara superweapon. Combined with the weakened state the Goa'uld are left in after their war with the Replicators, this resulted in the fall of the System Lords and the collapse of the Goa'uld Empire.[72] Shortly after, the Free Jaffa Nation is declared, with Dakara being made the capital.[71] Two seasons later, Adria sets course for Dakara, destroying the weapon and conquering the planet in the process.[73] After the loss of Dakara, the Free Jaffa Nation begins to fracture into several warring factions, some of which blame the Tau'ri for the devastation of Dakara.[74] In Stargate: The Ark of Truth SG-1 returns to the ruins of Dakara in search of the weapon that could stop the invasion of the Milky Way galaxy by the Ori Crusade.

Unlike what happened in the Milky Way, the human population of the Pegasus Galaxy is a product of Ancient seeding. The Lanteans arrived in the Pegasus Galaxy via the Ancientcity ship of Atlantis. As there was seldom interbreeding between the Ancients and humans, the ATA gene is virtually non-existent amongst the natives of Pegasus. Few human races in Pegasus surpass Earth in technological advancement, as the Wraith destroy any such civilizations as potential future threats to their dominance.

Atlantis is an Ancient city equipped with intergalactic hyperdrive engines that serves as the base of operations for the main SGA characters, from which they explore other planets through the Stargate. According to the mythology of the show, the city was built by an advanced race known as the Ancients originally as a central outpost in prehistorical Antarctica, until an unexplained crisis—involving a virulent plague—forced them to relocate the city to the planet Lantea in the Pegasus Galaxy. The Ancients (known as "Ancestors" to the denizens of Pegasus, "Lanteans" to the Wraith) submerged the city around 8,000 BCE to evade Wraith detection and returned via stargate to Earth, where survivor recollections formed the basis for the ancient Greek accounts of Lost City of Atlantis. As the humans from Earth inhabit the fabled City of the Ancestors after the series pilot of Stargate Atlantis, some Pegasus cultures believe the SGA members to be the Ancients returned.[4][76]

Ascension is a process by which sufficiently evolved sentient beings may shed their physical bodies and live eternally as pure energy on a higher plane of existence, where their capacity for learning and power grows exponentially. It is a mental, spiritual, or evolutionary enlightenment that can arise as the direct result of achieving a certain level of wisdom and self-knowledge. Ascension was once employed by the Ancients as a means to avoid several issues threatening their species with extinction, but it is sought by major powers on Earth and other races such as the Jaffa later. The concept is introduced in the SG-1 season 3 episode "Maternal Instinct" and becomes a central theme of Stargate SG-1 and Stargate Atlantis.

Ascension can happen in one of two ways: evolutionarily or spiritually. Ascension can occur when a human evolves the ability to use approximately 90% of his or her brain capacity.[77] The Ancients who ascended naturally reached this point without the aid of technology. They, however, developed the DNA Resequencer, a device capable of enhancing humans so that they would gain telepathy; telekinesis; superhuman senses, speed, and strength; precognition; perfect health; the ability to self-heal rapidly and the power to heal by touch; and the ability to use many parts of their mind and fully focus on a single thing.[78] Spiritual ascension can occur through meditation when one is pure of spirit and in the search for enlightenment,[71] has a fully opened mind,[79] and has shed one's fears and attachment to the mortal world.[80] In the process of ascension through meditation, many beings obtain the same supernatural abilities that users of the DNA resequencer receive.

An ascended Ancient's main rule is noninterference in mortal affairs. If broken, this rule may result in forceful de-ascension or other punishment by the other ascended beings.[81] The Ori, on the other hand, seek to increase their power by any means, including destroying their once-brothers, the Ancients, in a crusade against the Milky Way Galaxy. The power of an ascended being can be negated through the Sangraal, a device that the Ancient Merlin gave up his life to create to battle the Ori.[82]